Field of the Invention
The present invention relates to a polarization acquisition apparatus used to acquire polarization information from captured images.
Description of the Related Art
Rotating a polarizing filter provided on an image capturing optical path enables controlling an amount of light reflected by an object. For example, when image capturing of an underwater object is performed, removing a reflected light from a water surface by the polarizing filter enables providing an image in which the object is clearly image-captured. Moreover, when image capturing of trees is performed, reducing a reflected light from leaves enables providing a colorful image.
Japanese Patent Laid-Open No. 2011-191469 discloses an intermediate lens barrel attached between a camera and an interchangeable lens and provided with a polarizing filter and a mechanism rotating the filter. Japanese Patent Laid-Open No. 2009-232347 discloses a camera that acquires multiple images while rotating a polarizing filter or inserting and removing the filter into and from an optical path to change a degree of a polarizing filter effect.
On the other hand, Japanese Patent Laid-Open No. 11-041514 discloses a camera capable of removing, by using polarization information acquired from a captured image, a specular reflection component from the captured image. Furthermore, Japanese Patent Laid-Open No. 2012-080065 discloses an image sensor provided with a wire-grid polarizer to make polarized lights whose polarization directions are mutually different enter multiple pixels, thereby being capable of extracting polarization information including mutually different items.
However, the polarizing filters disclosed in Japanese Patent Laid-Open Nos. 2011-191469 and 2009-232347 can only adjust their polarizing filter effects on one captured image uniformly, that is, cannot provide mutually different polarizing filter effects on mutually different areas of the captured image. In addition, image capturing using these polarizing filters makes it impossible to adjust their polarizing filter effects on the captured image after the image capturing.
Moreover, the cameras disclosed in Japanese Patent Laid-Open Nos. 11-041514 and 2012-080065 each need to be a camera dedicated for acquiring the polarization information and to use illumination light dedicated therefore, which restricts objects to be image-captured and image capturing conditions.